The idea that the Biolizard and Shadow almost did the same revenge plot is also really interesting. They both were parts of Gerald's plot to ensure the ARK crashed, and both got brainwashed into doing so (how else would the Biolizard know to fuse to the ARK?). The only difference is that Shadow was intelligent enough to be reasoned with and could redeem himself, while the Biolizard was nothing but a disgusting perversion of nature that had to be killed.